Mitochondrial fusion protein MFN2 interacts with the mitostatin-related protein MNS1 required for mouse sperm flagellar structure and function.
Mitochondrial fusion protein MFN2 interacts with the mitostatin-related protein MNS1 required for mouse sperm flagellar structure and function.
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作者：
Vadnais ML;Lin AM;Gerton GL
纤毛和精子鞭毛有许多共同的结构特征。减数分裂特异性核结构蛋白1（MNS 1）是一种新近发现的蛋白质，在减数分裂后精子细胞中大量表达，是鞭毛和运动纤毛形成所必需的。为了探索MNS 1的可能功能，我们进行了BLAST搜索，并确定其与保守结构域pfam 13868同源，例如丝裂他汀。这种蛋白质与线粒体融合蛋白2（MFN 2）相互作用，后者是一种参与调节线粒体与亚细胞器结合的蛋白质。我们推测精子中MFN 2和MNS 1之间的关联参与鞭毛的生物发生和功能。在本文报道的研究中，MFN 2在纤毛含量高的小鼠生殖和体细胞组织中被发现，而MNS 1在生殖组织中作为两个紧密迁移的条带存在。有趣的是，丝裂抑制素也存在于生殖组织中。RT-PCR检测结果显示，Mfn 2在睾丸中表达，与Mns 1和mitostatin相似。此外，Mfn 2和Mns 1的表达减少粗线期精母细胞凝聚精子细胞通过定量RT-PCR评估。免疫共沉淀证实了MFN 2和MNS 1在生精细胞中的相关性。间接免疫荧光结果表明，MFN 2和MNS 1共定位于新鲜收集的附睾尾部精子的精子鞭毛。在附睾精子的头部和尾部，MFN 2与中段相关，而MNS 1则存在于整个精子尾部。在生精细胞中，MFN 2可见于线粒体，MNS 1存在于整个细胞质中。MFN 2和MNS 1存在于精子的耐洗涤剂鞭毛结构中。这些结果表明，MFN 2和MNS 1存在于生精细胞中，并且是精子鞭毛的组成部分，表明它们在鞭毛生物发生和/或功能中起作用。
Cilia and the sperm flagellum share many structural properties. Meiosis-specific nuclear structural 1 (MNS1) is a recently characterized protein that is abundantly expressed in post-meiotic spermatids and is required for proper flagellar and motile cilia formation. To explore the possible functions of MNS1, we performed a BLAST search and determined it is homologous to the conserved domain pfam13868, exemplified by mitostatin. This protein interacts with mitofusin 2 (MFN2), a protein that participates in regulating mitochondrial associations to subcellular organelles. We hypothesized that an association between MFN2 and MNS1 in the sperm is involved in flagellar biogenesis and function. In the studies reported here, MFN2 was found in murine reproductive and somatic tissues high in ciliary content while MNS1 was present as two closely migrating bands in reproductive tissues. Interestingly, mitostatin was also present in reproductive tissues. Similar to Mns1 and mitostatin, Mfn2 was expressed in the testis as detected by RT-PCR. In addition, Mfn2 and Mns1 decreased in expression from pachytene spermatocytes to condensing spermatids as assessed by quantitative RT-PCR. Co-immunoprecipitation demonstrated an association between MFN2 and MNS1 in spermatogenic cells. Indirect immunofluorescence indicated that MFN2 and MNS1 co-localized to the sperm flagellum in freshly collected cauda epididymal sperm. MFN2 associated with the midpiece while MNS1 was present throughout the sperm tail in caput and cauda epididymal sperm. In spermatogenic cells, MFN2 was seen in the mitochondria, and MNS1 was present throughout the cell cytoplasm. MFN2 and MNS1 were present in detergent-resistant flagellar structures of the sperm. These results demonstrate that MFN2 and MNS1 are present in spermatogenic cells and are an integral part of the sperm flagellum, indicating they play a role in flagellar biogenesis and/or function.